Coil-wedge.



A. B. FIELD.

COIL WEDGE.

APPLICATION FILED AIIG.2, I9I3.

1,150,022. PmnIedAug. 17,1915.

\ www UNITED STATES PATENT OFFICE.

ALLAN B. FIELD, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC ANI)4 MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

COIL-WEDGE.

Specification of Letters Patent.

Patented Aug. 17, 1915.

Application led August 2, 1913. Serial No. 782,566.

To au whom it may con cern Be it known that I, ALLAN B. FIELD, a subject of the King of England, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Coil-Wedges, of which the following is a specication.

Myinvention relates to dynamo-electric machines, and it has special reference to coil-retaining wedges adapted for use in such machines.

The object of my invention is to provide a device of the above-indicated character which shall be inexpensive and simple to manufacture, rugged, compact and convenient in construction, and which shall secure for the machine in which it is embodied, the well-known advantages of partially closed slots.

As is well understood by those skilled in the art, in the cores of dynamo-electric machines it is desirable to obtain at the air gap an approximately unbroken area of magnetizable material to effect a uniform distribution of the flux and decrease the leakage thereof, and to reduce the reluctance of the air gap. At the same time, the advantages of the open slot, as regards convenience and the saving in time and labor while assembling the coils on the core, are too obvious to require pointing out. Hence arises the more or less common expedient of employingv coil-retaining wedges that embody magnetizable material. For mechanical and magnetic reasons, the outer sheath must be very thin in order to permit the wedge vto be securely held in position by the small grooves which are usually provided inV the teeth of open-slot machines, and in order to minimize the length of the magnetic circuits.

In the prior art, many coil-retaining wedges have been devised, all of which have been subject to one or both of the following defects: A continuous metal envelop or sheath for the wedge has been employed, thereby, as it were, short-circuiting the laminatiorisz of' .the core. and decreasing their effectiveness in preventing losses from eddy currents, or thewedging means has comprised several. separate, or more or less unstably assembied, .magnetizable and associated insulatingportions.

According to my present invention, I provide a unitary wedge that is adapted to fit in the usual grooves in the core teeth and that comprises a plurality of suitable magnetizable members spaced apart by an insulating member and a thin envelop of a suitable hard insulating material, such as bakelite paper or the like', which products are deemed suciently well known in the art to make description thereof unnecessary.

By reason of the construction just described, a strong, compact. and convenient wedging member is obtained which secures to the machine employing it the above-mentioned advantages of `partially closed slots without embodying either 'of the disadvantageous features of the prior art hereinbefore pointed out.

In the accompanying drawing Figure l is a view in section of a portion of the core of a dynamo-electric machine ,embodying my invention and Fig. 2 is a view, in perspec-. tive, of a wedge with parts broken away to show the details. 4

Referring to the drawing, a section of a `core l of a dynamo-electric machine is provided with the usual teeth 2 and with substantially parallel-sided slots B-in which a plurality of coils 4L are disposed in any wellknown fashion. The teeth 2 are severally .provided on both sides near their free ends with grooves 5, as is more or less customary.

A plurality of unitary wedges 6 are severally disposed in confronting grooves 5 of adjacent teeth 2 to retain the coils 4 in position. Y

The wedges 6 severally comprise a plurality of magnetizable members 7, an 1nter mediate spacing member 8 and a thin enveloping member 9. The magnetizable members 7 severally constitute bundles of iron wires to reduce internal eddy current paper.

The method of making the wedges 6 is as follows: A plurality ofbundles of the iron Wires 7 are inserted within the edges of the vciently strong mechanically and the enveloping member 9 is not thick enough to seriously interfere With the magnetic functions of the magnetizable members 7 I do not Wish'to be restricted to the specie structural details herein set forth, but desire that only such iimitations shall .be

imposed as are indicated in the appended` claims.

I claim as my invention: t l. The method of making a coil-retaining Wedge for openslot ,dynamo-electric machines that consists in flattening an insulat' ing tube, disposing therein a plurality of magnetizable members, disposing insulating material intermediate .said members and pressing the assembled body to a mined shape.

2. The method of Vmaking acoil-retaining wedge for open-slot dynamo-electric mapredeterchine that consists lin flattening-,a tube of" resinous insulating material, inserting therein a plurality of divided magnetizable members, lnserting insulating material intermediate said members, treating theassemvbled body with 'an insulating fluid, and

pressing the saidbody to a predetermined shape.

3.' The method of making a coil-retaining Wedge for open slot dynamo electric -ma chines that consists in attening a tube of resinous insulating material, inserting therein a pluralityI of stranded magnetizable members, inserting inherently rigid insulating material intermediate said members, im-

pregnating the assembled body with an in sulating fluid, and pressing the said body to a predetermined shape and hardness.

4. i coil-retaining Wedge for open-slot dynamo-electric machines comprising a plurality of magneti'zable members,van intermediate insulating member and an enveloping insulating member, said members being impregnated with an insulating fluid and pressed to form a unified body.

5. A coil-retaining wedge for open-slot- 'A dynamo-electric machines comprising a plurality ofvstranded magnetizable members, an intermediate rigid insulating member and an enveloping member of hard insulat- 'ing material, said members being impregnatedowith an insulating fluid and pressed to form au nied body.A

In testimony whereof, I have hereunto J. A.,KUYsn-n, B. B. Hnms.

-subs'cribed my naine this 26th day of July 

